This invention relates to a method of manufacturing stockings and like articles having a Jacquard pattern over ribbed knitwork made of plain and purl stitches, as well as to a circular knitting machine carrying to effect such a method.
The prior art stockings, socks, hoses and similar, of the type having a Jacquard pattern over ribbed knitwork, have been produced on double cylinder circular knitting machines. As known, the knitting process is carried out with at least two thread feeds, and by knitting with the needles partly in the upper needle cylinder and partly in the lower one. More specifically, the leg portion is advantageously knitted with the needles alternatively in one needle cylinder and the other, thereby all the upper cylinder needles pick up the thread from each feed at every knitting course, whereas the lower cylinder needles pick up the thread each from one feed only during a knitting course according to the pattern to be obtained. On completion of the leg portion, part of the upper cylinder needles hold the knitwork while the rest of the needles are transferred into the lower needle cylinder, wherein they all cooperate to form the heel portion of the stocking or like articles. The corresponding needles are then returned to the upper needle cylinder and the foot portion is knitted in a manner substantially similar to the leg portion knitting step. The toe, when not directly closed on the machine by any known method, may be left open and knitted like a heel, whereby a new transfer and knitting step is effected as described hereinabove, the toe being then closed by sewing.
Such machines permit wide variations in the pattern and provide highly satisfactory products. However, they are not entirely free from drawbacks, which are generally considered unimportant when compared to the aforementioned capabilities, and thus tolerated.
The shortcomings reside mainly in the high cost of such double cylinder circular knitting machines, their bulk, and especially their height, the need for qualified personnel both for their operation and adjusting, and their comparatively limited production rate. The latter is indeed limited by such factors as the complexity and fragility of the machine, which permit no rotation or reciprocation of the needle cylinders at a very high speed, and by the need of transferring of the needles from one needle cylinder to the other, which is a frequently repeated step during the knitting of a stocking and like article, thus bringing about operational times which are inefficient from the knitwork production point of view. Indeed, the transfer movement requires each time that the needle be unhooked from the respective transfer slider or jack in one needle cylinder and hooked by the corresponding transfer slider in the other needle cylinder, in addition to the transferring of the needle proper.